THYROID GLAND. 355 



Those substances which bear a close relation to the functions of the 

 gland seem to be of special interest. 



The complete extirpation, as also the pathological destruction, 6f the. 

 thyroid gland causes great disturbances, ending finally in death. In 

 dogs, after the total extirpation, a disturbance of the nervous and muscular 

 systems occurs, such as trembling and convulsions, and death generally 

 supervenes shortly after, most often during such an attack. The researches 

 of GLEY, VASSALE and GENERALI 1 upon various animals have shown 

 that for the success of the operation it is of the greatest importance 

 whether the parathyroids, discovered by SANDSTROM, 2 are removed at 

 the same time or not. In herbivora (rabbits) because of the anatomical 

 relations, the parathyroids are seldom extirpated in the operation of 

 the removal of the thyroid, the tetany does not regularly occur and 

 the disturbance in metabolism is most striking. If these glands are 

 not extirpated in dogs the tetany also does not appear and the dis- 

 turbances in metabolism occur. In human beings, after the removal of 

 the gland by operation, different disturbances appear, such as nervous 

 symptoms, diminished intelligence, dryness of the skin, falling out of 

 the hair, and, on the whole, those symptoms which are included under 

 the name cachexia thyreopriva, death coming gradually. Among these 

 symptoms must be mentioned the peculiar slimy infiltration and exuber- 

 ance of the connective tissue called myxoedema. 



All these conditions indicate that the thyroids belong to those glands 

 with internal secretion, so called endocrinogenic glands. The most con- 

 vincing proof of this is the fact that the ordinary symptoms do not occur 

 if a small piece of the gland is allowed to remain in the body, or even 

 when a piece of the gland is transplanted in any part of the body. A 

 further proof of practical importance is that the injurious results from 

 removal of the thyroids can be counteracted by the introduction of arti- 

 ficial extracts of the thyroid gland into the body or by feeding with 

 thyroid glands. 



Of the disturbances in metabolism which occur on the extirpation 

 or reduction of the thyroid function (athyreoiclismus or hypothyreoid- 

 ismus) we must especially mention the reduction in the protein catabolism 

 which in a starving dog without thyroids may fall to about one-half of 

 the starvation protein metabolism in a normal dog of the same size 

 (FALTA and collaborators 3 ) . The reverse is observed when large quantities 

 of the thyroid gland substance is fed, namely, a strong increase in the 

 protein metabolism, besides certain other symptoms. BASEDOW'S disease 



1 Gley, Compt. rend. soc. biol., 1891, and Arch, de Physiol (5), 4; Vassale and 

 General!, Arch. Ital. d. Biol., 25 and 26. 



2 Upsala Lakaref. Forh., 15 (1880). 



3 Eppinger, Falta and Rudinger, Zeitschr. f. klin. Med., 66. 



